She's a goddess.
If she gave you a "proper" fight, the game would have ended. There would be no one left.
True and that would be as much true for C and Arcas (if last is in game likely) and they tried to go one one one or even team on one with either sister. One reason why I try to look for how MC and his coterie could make a difference, Arigon seems to shoot down the yellow eyes power as being not that rare, so what might it be beyond the vampire slaying sword +20 the Temple may hold, Remember they are there to either facilitate or stop the rise of one, both or either sister. I am still not 100% convinced either C or the Temple is team I and they might have access to something even the sisters would not like depending on who started that temple.).
Well after the meeting underground pretty unlikely MC is a rebirth of one of or both old sisters lover and can be a bridge. She did not recognize him for sure, so I guess any threesome with both sisters will be at best as a blood bag slave to them.
So either we are left with a situation where MC and his coterie somehow swing it in favor of one sister by something seemingly insignificant, but enough for the other sister to take advantage I suspect. Just a fraction of a second might do it if both sisters are very equal in power.
Other option is that MC is in the end is just an observer and we follow the story of the rise from his pov and he will have no impact on that in the end or any influence who will win, if either will. Might seem not very satisfying to us as players, but with the power differentials that does make sense. In the end even C would be just a blood bag to either of the sisters, a very sweet one considering the other vampiric options around and if dear Arcas is around and still obsessed with his mommy, well he will be almost as sweet and if would succeed in defeating mommy be desirable blood bag number one for either sister.
Even if he thought he was invincible, well he also plays in another league now and if has cunningly hid himself for 4 millennia while hunting Mommy might be wise enough to run like hell. hell it is not even impossible if I had C create Mc just as bloodbag for her and the protecting she did was just to make sure her sister would not feed on him first.
Just to annoy Arigon a bit, what if Arcas would not be after Mommy, but after Mc. With his ego he might dislike no longer being the only only childe of C and he is what happened to every other childe C ever might have had. Would make him quite the jealous character though.
Also we still have that little loose end of the attack on Sharon at start, he or she should still be around somewhere, most sense makes C indeed or maybe even Arcas if he noticed a brother had risen unexpectedly or Fabian told him. Question would be why he did not take out MC in that case if after C while MC still super weak, maybe arrogance and wanting to train him a bit before harvesting him, that would probably hold for a few more centuries for Mc though, before he would even start to see MC as a real threat. E and I can likely be dismissed as options though for that attack, so who was it? I tend to suspect now it will be more related to the archons subplot where Mc can shine and show some ass kicking skills to make us players feel better about him.